Follicle-Stimulating Hormone Abnormalities Workup

Updated: Apr 01, 2020
  • Author: Serge A Jabbour, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Laboratory Studies

Perform additional laboratory studies in men presenting with low follicle-stimulating hormone (FSH) levels.

  • Regarding LH and testosterone, most patients with low FSH levels also have low LH and low testosterone levels. A few cases of isolated FSH deficiency exist in which LH and testosterone levels are within reference ranges but the sperm count is low.

  • For prolactin, patients with high prolactin levels frequently manifest low FSH, LH, and testosterone levels, all of which may resolve with normalization of prolactin levels.

  • In men with low FSH levels and feminizing features, including gynecomastia, serum estradiol measurement is indicated to exclude an estrogen-secreting tumor (testes, adrenals).

  • Semen analysis is performed to assess fertility.

In men presenting with high FSH levels, the underlying etiology is related to primary hypogonadism or a gonadotroph adenoma. Therefore, the following lab tests are indicated:

  • For LH and testosterone, patients with primary hypogonadism have low testosterone levels with high LH and FSH levels. Patients with gonadotroph adenomas usually have high FSH levels with normal LH and testosterone levels; occasionally, LH levels can be high, but testosterone levels are also high. Gonadotroph adenomas that secrete FSH may induce compression of normal pituitary cells, leading to low LH and testosterone levels.

  • In patients with gonadotroph adenomas, other pituitary hormone levels must also be assessed because macroadenomas may induce hypopituitarism. Serum TSH and free T4, morning cortisol and adrenocorticotropic hormone (ACTH), prolactin, and, occasionally, dynamic testing for GH may be necessary.

  • Obtain a peripheral leukocyte karyotype in men with congenital primary hypogonadism to determine if Klinefelter syndrome is present.

In women presenting with low FSH levels, additional testing should include determination of LH, estradiol, and prolactin levels. Thyroid disease should be excluded by measuring TSH and free T4. If hirsutism is present, serum testosterone and dehydroepiandrosterone sulfate (DHEAS) testing should be performed. Moreover, additional testing such as determination of the serum 17-hydroxyprogesterone level before and after ACTH stimulation may be performed if congenital adrenal hyperplasia is suggested.

In women with high FSH levels, the differential diagnosis is either ovarian failure or gonadotroph adenoma. The following points should be remembered:

  • In women with ovarian failure, both FSH and LH levels rise. In women with gonadotroph adenomas, FSH levels are usually high, but LH levels remain within reference ranges. Other pituitary hormone abnormalities may be present.

  • If the diagnosis of ovarian failure is confirmed in patients younger than 30 years, a karyotype evaluation should be performed to exclude Turner syndrome or the presence of Y chromatin material because of the high risk of gonadal tumors, mandating gonadectomy.

  • In the presence of a normal karyotype, autoimmune disease is likely (30% of these patients); therefore, assessment for autoimmune disorders, including thyroid or adrenal disease, is important. Testing may include TSH, antithyroid antibodies, morning serum cortisol, and ACTH evaluations, followed by an ACTH stimulation test if necessary.


Imaging Studies

In men or women with low follicle-stimulating hormone (FSH), high prolactin, or high FSH levels (the latter being suggestive of gonadotroph adenoma in the appropriate clinical setting), an MRI scan of the pituitary gland must be obtained.

In women with very high DHEAS levels (>700 mcg/dL), perform CT scanning of the adrenals to exclude an androgen-secreting tumor.

In women with very high testosterone levels (>200 ng/mL), perform imaging studies of the ovaries (CT scan, ultrasound).

In men with high estradiol levels, imaging of the testes (ultrasound) should be performed and, subsequently, the adrenals (CT scan) if the testicular ultrasound findings are normal.



In women with clinical features and laboratory findings suggestive of an ovarian tumor but with negative results from imaging studies, laparoscopy may be performed to help locate ovarian masses, which could be small and are frequently difficult to detect using routine imaging.